DSH-Engineering-Workflow: Adding a Five-Phase Engineering Workflow to DSH

`dsh-engineering-workflow` is a DSH community plugin designed to provide a controlled workflow for agent development and multi-step engineering tasks. By adding an "Engineering Workflow" preset, this plugin decomposes tasks into five gate-based stages: requirement clarification, plan approval, TDD implementation, parallel sub-agent execution, and validation wrap-up. Each stage corresponds to specific workflow skills, coordinated by the main skill `engineering-workflow`, preventing tasks from arbitrarily jumping between stages. During installation, Node.js version requirements must be met, and the plugin is added via the `dsh plugin` command, followed by restarting DSH or manually running a synchronization script to load the preset. Once enabled, new sessions can select this preset to load the full process discipline. This plugin